Under most circumstances, an unheralded 24-year-old putting up impressive numbers below the Double-A level isn't going to create much prospect buzz. When scouting reports line up with the performance, however, it makes for an intriguing breakout story.

That's especially true when you consider that Nationals righthander Nate Karns did not rank among the organization's Top 30 Prospects following any of his first three pro seasons. He's well on his way to receiving recognition this offseason now that he leads the Washington system with a 1.92 ERA and 129 strikeouts.

The fact that Karns has battled back from shoulder surgery and that he's continuing to hone revamped mechanics make his story even more compelling.

Karns spent the first two months of the season with low Class A Hagerstown, his first exposure to full-season ball, and earned an early-June promotion to high Class A Potomac. Touched for nine runs in his first two Carolina League starts, Karns settled in nicely afterward and reeled off eight good starts in a row, going 7-0, 1.03 with 59 strikeouts versus 11 walks and 24 hits allowed over 52 innings.

Between the two Class A stops, Karns had struck out 11.3 batters per nine innings, which trailed only Athletics righty Dan Straily and Diamondbacks lefty Andrew Chafin for the minor league lead.

"My biggest goal this year has just been to stay on the field," Karns said. "I've already missed a lot of time getting healthy. At this point, though, I can't afford another setback, so I'm just trying to slow things down as much as possible."

Regardless of his age and level, Karns has worked his way into the second tier of Nationals pitching prospects, behind the likes of righthanders Alex Meyer and Lucas Giolito and lefty Sammy Solis, but on par with anyone else in the organization.

"We basically started completely from scratch with him," Nationals farm director Doug Harris said. "He's done an excellent job commanding and leveraging his fastball this year, which he's getting up to 96 (mph) and the (spike) curveball is a swing-and-miss pitch."

Worthwhile Flier

Physically imposing at 6-foot-5 and 230 pounds, Karns' stuff has never been the issue.

As a senior at Martin High in Arlington, Texas, he attracted attention from scouts for both his physicality and a peak velocity of 95 mph. Some teams liked the Texas commit as high as the third round of the 2006 draft, but mechanical issues cost Karns consistency in terms of both velocity and command, and he fell to the Astros in the 10th round. He did not sign.

Karns spent his freshman year at North Carolina State working in a piggyback role, starting eight games for the Wolfpack but going just three or four innings at a time. He transferred back home to Texas Tech for the 2008 season, and he continued to learn how to pitch and iron out his mechanics.

Karns again positioned himself to go in the top three rounds of the 2009 draft after flashing a 95-96 mph fastball and a plus curveball in the Cape Cod League after the 2008 season. But inconsistency again plagued Karns during his junior year. He had trouble throwing strikes and locating his pitches when he did find the zone. One scout said at the time, "He looks like Roger Clemens in the bullpen, but he gets whacked (in games)."

The Nationals took a flier on Karns in the 12th round and signed him with a $225,000 bonus, but he didn't actually take the field that summer or the next.

Karns missed all of 2010 season due to illness, arm fatigue and, eventually, labrum surgery—a procedure that can be career ending. He made a complete recovery, and the Nationals see positive effects from the surgery and rehabilitation.

"Nathan deserves all the credit," Washington scouting director Kris Kline said. "He's an extremely hard worker and strong as a bull—and his arm action is actually a lot cleaner than it was prior to surgery. Over the course of the past year, he's throwing with more ease and repeating his delivery very nicely."

Needless to say, Karns will not be rushed as the season draws closer to an end. While he doesn't have a lot of mileage on his arm, he already had thrown 103 innings this year—twice as many as he's ever pitched in a season and one-third of the total he's thrown since 2007.

Karns opened the season in the Hagerstown bullpen, but since returning him to the rotation in May the Nationals have instituted an innings limit—a number they have set in stone but were not willing to discuss.

Karns sits in the low 90s, touches 95 mph, and delivers his fastball on a steep plane, mixing in a downer, low- to mid-80s curveball that projects to be at least average. He shows surprising feel for his changeup despite his lack of mound time, giving him the potential to develop three legitimate pitches.

He said he's overhauled a laundry list of mechanical issues since being drafted, and that trying to get rid of all his bad habits has been a difficult, but rewarding, process.

"My arm slot was too high and I was spinning off the mound," Karns said. "So just trying to be consistent with staying on line with the catcher, staying back and on top of the ball has made a big difference."

While it's difficult to predict the future for a pitching prospect who had major shoulder surgery, Karns has the ultimate ceiling of a mid-rotation starter or late-inning reliever. For now, patience is a virtue to Karns and the Nationals player-developmental staff.